Protein, Free Amino Acid and Polyamine Contents during Development of Hairy Root Nicotiana tabacum Plants

Summary Clones of transgenic tobacco plants, regenerated from transformed roots arising from Agrobacterium rhizogenes inoculation, were analyzed both in vivo under greenhouse conditions and in in vitro culture. Transformed plants displayed phenotypic alterations, referred to as hairy root syndrome. These traits were particularly accentuated in some plants, designated supertransformed, and seemed to be modulated by in vivo versus in vitro culture conditions. The comparison of protein, amino acid and polyamine levels between normal and transformed plants revealed alterations in nitrogen metabolism. In fact, under in vivo conditions apices and leaves of transformed plants displayed lower levels of glutamine and asparagine. The evolution in total polyamine content was generally an increase from 6-13 weeks, followed by a decrease at 20 weeks, the transformed tissues always containing lower polyamine levels than the normal ones. The major difference in vivo consisted in a strong reduction in the TCA-soluble and - insoluble bound polyamines, particularly evident in the leaves of transformed and supertransformed plants. On the whole, significant differences were found between in vivo and i n vitro conditions: TCA-soluble bound polyamines were undetectable in both transformed and untransformed in vitro plantlets; in addition, supertransformed in vitro plantlets contained unexpectedly high levels of chlorophyll, proteins, amino acids and free polyamines compared with their counterparts grown in soil.